So I have 3 concealers.  Obviously the much-hyped Collection 2000 Lasting Perfection, which I love, but find medium too light and dark too dark.  The perils of small shade ranges.  Next is Mac studiocover.  More or less the same, but much closer to my skintone in NC35.  Lasting power not nearly as good as the Collection 2000. Lastly, for under-eyes I have the Garnier Roll-on thingy in Medium.  Verrrrryyyy good for under the eyes.  Good colour match.  But I wanted more.  I wanted H E A V Y   D U T Y.  I've tried Mac Studio Finish - the thick, supposedly tattoo-covering one.  But I was having bad skin days at the time and it broke me out.  I've been procrastinating about getting the Soap and Glory one for aaaaaaaaaages and the other day, just took the plunge.  
I like how it's such a clever little product.  One concealer for under-eyes, one for blemishes, and a setting powder.  Coverage is  fair, I think along the lines of Mac Moisturecover, but in the form of Studio Finiish!  I picked up medium, and the colours are just perfect for me.  Plus the little setting powder is geee-neee-ass.  
I like this product a lot - its so convenient and dinky!  But, what would make this better for me would be a little more coverage.  I have dark patches from spot scars on my chin, and it doesn't quite cover them fully.  I think I'll be sticking to all my normal concealers, plus this one, plus maybe trying another sample of Mac Studio Finish.  After all, variety is the spice of life, and a girl can never have too many concealers!
In the above pic you can just about make out the swatches - this is unblended.  The Left is the under-eye concealer, the right is the blemish concealer and above is the powder.  Even unblended the colours are a good match.
I hope this helped!
Love A.x